Add Python 3.10 wheel builds

Author: AlexanderWells-diamond

.github/workflows/code.yml

@@ -35,7 +35,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python: [cp36, cp37, cp38, cp39]
+        python: [cp36, cp37, cp38, cp39, cp310]
 
         include:
           # Put coverage and results files in the project directory for mac

setup.cfg

@@ -14,6 +14,7 @@ classifiers =
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
 
 [options]
 packages = softioc